Present invention relates to an auxiliary portable power supply device for use in conjunction with battery-powered appliances, particularly appliances such as lightweight radios and tape playing devices.
In recent times there has been a substantial increase in the number and type of battery operated portable devices. This is particularly true of small stereo radio/tape player devices of the type employing small lightweight headphones to facilitate use during exercise and sporting activities.
The use of such devices during exercise, jogging, bicycling and the like has required that the device be made as compact and as lightweight as possible, ideally so as to be attached to a belt or article of clothing without causing undue discomfort. Such size and weight limitations have therefore caused many of the devices to be designed to operate at 3 volts using two standard AA cells.
In the typical device two premium alkaline AA cells will provide approximately 12 hours of useful operating time. Attempts to design external auxiliary power sources for such devices have heretofore involved large cumbersome battery packs which often weighed as much as, or more than, the device being powered. They also constituted an additional unit to be separately clipped or attached to the belt or article of clothing.